String precision pitfalls

While you may use the printf() functions to format UTF-8 strings, notice that the precision of a %Ns parameter is interpreted as the number of bytes, not characters to print. On top of that, the GNU libc implementation of the printf() functions has the "feature" that it checks that the string given for the %Ns parameter consists of a whole number of characters in the current encoding. So, unless you are sure you are always going to be in an UTF-8 locale or your know your text is restricted to ASCII, avoid using %Ns. If your intention is to format strings for a certain number of columns, then %Ns is not a correct solution anyway, since it fails to take wide characters (see g_unichar_iswide()) into account.

Note also that there are various printf() parameters which are platform dependent. GLib provides platform independent macros for these parameters which should be used instead. A common example is G_GUINT64_FORMAT, which should be used instead of %llu or similar parameters for formatting 64-bit integers. These macros are all named G_*_FORMAT; see Basic Types.

g_strdup ()

gchar *
g_strdup (const gchar *str);

Duplicates a string. If str is NULL it returns NULL. The returned string should be freed with g_free() when no longer needed.

g_strndup ()

gchar *
g_strndup (const gchar *str,
           gsize n);

Duplicates the first n bytes of a string, returning a newly-allocated buffer n + 1 bytes long which will always be nul-terminated. If str is less than n bytes long the buffer is padded with nuls. If str is NULL it returns NULL. The returned value should be freed when no longer needed.

To copy a number of characters from a UTF-8 encoded string, use g_utf8_strncpy() instead.

g_strdupv ()

gchar **
g_strdupv (gchar **str_array);

Copies NULL-terminated array of strings. The copy is a deep copy; the new array should be freed by first freeing each string, then the array itself. g_strfreev() does this for you. If called on a NULL value, g_strdupv() simply returns NULL.

g_strnfill ()

gchar *
g_strnfill (gsize length,
            gchar fill_char);

Creates a new string length bytes long filled with fill_char . The returned string should be freed when no longer needed.

g_stpcpy ()

gchar *
g_stpcpy (gchar *dest,
          const char *src);

Copies a nul-terminated string into the dest buffer, include the trailing nul, and return a pointer to the trailing nul byte. This is useful for concatenating multiple strings together without having to repeatedly scan for the end.

g_strstr_len ()

gchar *
g_strstr_len (const gchar *haystack,
              gssize haystack_len,
              const gchar *needle);

Searches the string haystack for the first occurrence of the string needle , limiting the length of the search to haystack_len .

g_strrstr ()

gchar *
g_strrstr (const gchar *haystack,
           const gchar *needle);

Searches the string haystack for the last occurrence of the string needle .

g_strrstr_len ()

gchar *
g_strrstr_len (const gchar *haystack,
               gssize haystack_len,
               const gchar *needle);

Searches the string haystack for the last occurrence of the string needle , limiting the length of the search to haystack_len .

g_str_has_prefix ()

gboolean
g_str_has_prefix (const gchar *str,
                  const gchar *prefix);

Looks whether the string str begins with prefix .

Since: 2.2

g_str_has_suffix ()

gboolean
g_str_has_suffix (const gchar *str,
                  const gchar *suffix);

Looks whether the string str ends with suffix .

Since: 2.2

g_strcmp0 ()

int
g_strcmp0 (const char *str1,
           const char *str2);

Compares str1 and str2 like strcmp(). Handles NULL gracefully by sorting it before non-NULL strings. Comparing two NULL pointers returns 0.

Since: 2.16

g_str_to_ascii ()

gchar *
g_str_to_ascii (const gchar *str,
                const gchar *from_locale);

Transliterate str to plain ASCII.

For best results, str should be in composed normalised form.

This function performs a reasonably good set of character replacements. The particular set of replacements that is done may change by version or even by runtime environment.

If the source language of str is known, it can used to improve the accuracy of the translation by passing it as from_locale . It should be a valid POSIX locale string (of the form language[_territory][.codeset][@modifier]).

If from_locale is NULL then the current locale is used.

If you want to do translation for no specific locale, and you want it to be done independently of the currently locale, specify "C" for from_locale .

Since: 2.40

g_str_tokenize_and_fold ()

gchar **
g_str_tokenize_and_fold (const gchar *string,
                         const gchar *translit_locale,
                         gchar ***ascii_alternates);

Tokenises string and performs folding on each token.

A token is a non-empty sequence of alphanumeric characters in the source string, separated by non-alphanumeric characters. An "alphanumeric" character for this purpose is one that matches g_unichar_isalnum() or g_unichar_ismark().

Each token is then (Unicode) normalised and case-folded. If ascii_alternates is non-NULL and some of the returned tokens contain non-ASCII characters, ASCII alternatives will be generated.

The number of ASCII alternatives that are generated and the method for doing so is unspecified, but translit_locale (if specified) may improve the transliteration if the language of the source string is known.

Since: 2.40

g_str_match_string ()

gboolean
g_str_match_string (const gchar *search_term,
                    const gchar *potential_hit,
                    gboolean accept_alternates);

Checks if a search conducted for search_term should match potential_hit .

This function calls g_str_tokenize_and_fold() on both search_term and potential_hit . ASCII alternates are never taken for search_term but will be taken for potential_hit according to the value of accept_alternates .

A hit occurs when each folded token in search_term is a prefix of a folded token from potential_hit .

Depending on how you're performing the search, it will typically be faster to call g_str_tokenize_and_fold() on each string in your corpus and build an index on the returned folded tokens, then call g_str_tokenize_and_fold() on the search term and perform lookups into that index.

As some examples, searching for ‘fred’ would match the potential hit ‘Smith, Fred’ and also ‘Frédéric’. Searching for ‘Fréd’ would match ‘Frédéric’ but not ‘Frederic’ (due to the one-directional nature of accent matching). Searching ‘fo’ would match ‘Foo’ and ‘Bar Foo Baz’, but not ‘SFO’ (because no word has ‘fo’ as a prefix).

Since: 2.40

g_strlcpy ()

gsize
g_strlcpy (gchar *dest,
           const gchar *src,
           gsize dest_size);

Portability wrapper that calls strlcpy() on systems which have it, and emulates strlcpy() otherwise. Copies src to dest ; dest is guaranteed to be nul-terminated; src must be nul-terminated; dest_size is the buffer size, not the number of bytes to copy.

At most dest_size - 1 characters will be copied. Always nul-terminates (unless dest_size is 0). This function does not allocate memory. Unlike strncpy(), this function doesn't pad dest (so it's often faster). It returns the size of the attempted result, strlen (src), so if retval >= dest_size , truncation occurred.

Caveat: strlcpy() is supposedly more secure than strcpy() or strncpy(), but if you really want to avoid screwups, g_strdup() is an even better idea.

g_strlcat ()

gsize
g_strlcat (gchar *dest,
           const gchar *src,
           gsize dest_size);

Portability wrapper that calls strlcat() on systems which have it, and emulates it otherwise. Appends nul-terminated src string to dest , guaranteeing nul-termination for dest . The total size of dest won't exceed dest_size .

At most dest_size - 1 characters will be copied. Unlike strncat(), dest_size is the full size of dest, not the space left over. This function does not allocate memory. It always nul-terminates (unless dest_size == 0 or there were no nul characters in the dest_size characters of dest to start with).

Caveat: this is supposedly a more secure alternative to strcat() or strncat(), but for real security g_strconcat() is harder to mess up.

g_strdup_printf ()

gchar *
g_strdup_printf (const gchar *format,
                 ...);

Similar to the standard C sprintf() function but safer, since it calculates the maximum space required and allocates memory to hold the result. The returned string should be freed with g_free() when no longer needed.

The returned string is guaranteed to be non-NULL, unless format contains %lc or %ls conversions, which can fail if no multibyte representation is available for the given character.

g_strdup_vprintf ()

gchar *
g_strdup_vprintf (const gchar *format,
                  va_list args);

Similar to the standard C vsprintf() function but safer, since it calculates the maximum space required and allocates memory to hold the result. The returned string should be freed with g_free() when no longer needed.

The returned string is guaranteed to be non-NULL, unless format contains %lc or %ls conversions, which can fail if no multibyte representation is available for the given character.

See also g_vasprintf(), which offers the same functionality, but additionally returns the length of the allocated string.

g_printf ()

gint
g_printf (gchar const *format,
          ...);

An implementation of the standard printf() function which supports positional parameters, as specified in the Single Unix Specification.

As with the standard printf(), this does not automatically append a trailing new-line character to the message, so typically format should end with its own new-line character.

glib/gprintf.h must be explicitly included in order to use this function.

Since: 2.2

g_vprintf ()

gint
g_vprintf (gchar const *format,
           va_list args);

An implementation of the standard vprintf() function which supports positional parameters, as specified in the Single Unix Specification.

glib/gprintf.h must be explicitly included in order to use this function.

Since: 2.2

g_fprintf ()

gint
g_fprintf (FILE *file,
           gchar const *format,
           ...);

An implementation of the standard fprintf() function which supports positional parameters, as specified in the Single Unix Specification.

glib/gprintf.h must be explicitly included in order to use this function.

Since: 2.2

g_vfprintf ()

gint
g_vfprintf (FILE *file,
            gchar const *format,
            va_list args);

An implementation of the standard fprintf() function which supports positional parameters, as specified in the Single Unix Specification.

glib/gprintf.h must be explicitly included in order to use this function.

Since: 2.2

g_sprintf ()

gint
g_sprintf (gchar *string,
           gchar const *format,
           ...);

An implementation of the standard sprintf() function which supports positional parameters, as specified in the Single Unix Specification.

Note that it is usually better to use g_snprintf(), to avoid the risk of buffer overflow.

glib/gprintf.h must be explicitly included in order to use this function.

See also g_strdup_printf().

Since: 2.2

g_vsprintf ()

gint
g_vsprintf (gchar *string,
            gchar const *format,
            va_list args);

An implementation of the standard vsprintf() function which supports positional parameters, as specified in the Single Unix Specification.

glib/gprintf.h must be explicitly included in order to use this function.

Since: 2.2

g_snprintf ()

gint
g_snprintf (gchar *string,
            gulong n,
            gchar const *format,
            ...);

A safer form of the standard sprintf() function. The output is guaranteed to not exceed n characters (including the terminating nul character), so it is easy to ensure that a buffer overflow cannot occur.

See also g_strdup_printf().

In versions of GLib prior to 1.2.3, this function may return -1 if the output was truncated, and the truncated string may not be nul-terminated. In versions prior to 1.3.12, this function returns the length of the output string.

The return value of g_snprintf() conforms to the snprintf() function as standardized in ISO C99. Note that this is different from traditional snprintf(), which returns the length of the output string.

The format string may contain positional parameters, as specified in the Single Unix Specification.

g_vsnprintf ()

gint
g_vsnprintf (gchar *string,
             gulong n,
             gchar const *format,
             va_list args);

A safer form of the standard vsprintf() function. The output is guaranteed to not exceed n characters (including the terminating nul character), so it is easy to ensure that a buffer overflow cannot occur.

See also g_strdup_vprintf().

In versions of GLib prior to 1.2.3, this function may return -1 if the output was truncated, and the truncated string may not be nul-terminated. In versions prior to 1.3.12, this function returns the length of the output string.

The return value of g_vsnprintf() conforms to the vsnprintf() function as standardized in ISO C99. Note that this is different from traditional vsnprintf(), which returns the length of the output string.

The format string may contain positional parameters, as specified in the Single Unix Specification.

g_vasprintf ()

gint
g_vasprintf (gchar **string,
             gchar const *format,
             va_list args);

An implementation of the GNU vasprintf() function which supports positional parameters, as specified in the Single Unix Specification. This function is similar to g_vsprintf(), except that it allocates a string to hold the output, instead of putting the output in a buffer you allocate in advance.

The returned value in string is guaranteed to be non-NULL, unless format contains %lc or %ls conversions, which can fail if no multibyte representation is available for the given character.

glib/gprintf.h must be explicitly included in order to use this function.

Since: 2.4

g_printf_string_upper_bound ()

gsize
g_printf_string_upper_bound (const gchar *format,
                             va_list args);

Calculates the maximum space needed to store the output of the sprintf() function.

g_str_is_ascii ()

gboolean
g_str_is_ascii (const gchar *str);

Determines if a string is pure ASCII. A string is pure ASCII if it contains no bytes with the high bit set.

Since: 2.40

g_ascii_isalnum ()

gboolean
g_ascii_isalnum (gchar c);

Determines whether a character is alphanumeric.

Unlike the standard C library isalnum() function, this only recognizes standard ASCII letters and ignores the locale, returning FALSE for all non-ASCII characters. Also, unlike the standard library function, this takes a char, not an int, so don't call it on EOF, but no need to cast to guchar before passing a possibly non-ASCII character in.

g_ascii_isalpha ()

gboolean
g_ascii_isalpha (gchar c);

Determines whether a character is alphabetic (i.e. a letter).

Unlike the standard C library isalpha() function, this only recognizes standard ASCII letters and ignores the locale, returning FALSE for all non-ASCII characters. Also, unlike the standard library function, this takes a char, not an int, so don't call it on EOF, but no need to cast to guchar before passing a possibly non-ASCII character in.

g_ascii_iscntrl ()

gboolean
g_ascii_iscntrl (gchar c);

Determines whether a character is a control character.

Unlike the standard C library iscntrl() function, this only recognizes standard ASCII control characters and ignores the locale, returning FALSE for all non-ASCII characters. Also, unlike the standard library function, this takes a char, not an int, so don't call it on EOF, but no need to cast to guchar before passing a possibly non-ASCII character in.

g_ascii_isdigit ()

gboolean
g_ascii_isdigit (gchar c);

Determines whether a character is digit (0-9).

Unlike the standard C library isdigit() function, this takes a char, not an int, so don't call it on EOF, but no need to cast to guchar before passing a possibly non-ASCII character in.

g_ascii_isgraph ()

gboolean
g_ascii_isgraph (gchar c);

Determines whether a character is a printing character and not a space.

Unlike the standard C library isgraph() function, this only recognizes standard ASCII characters and ignores the locale, returning FALSE for all non-ASCII characters. Also, unlike the standard library function, this takes a char, not an int, so don't call it on EOF, but no need to cast to guchar before passing a possibly non-ASCII character in.

g_ascii_islower ()

gboolean
g_ascii_islower (gchar c);

Determines whether a character is an ASCII lower case letter.

Unlike the standard C library islower() function, this only recognizes standard ASCII letters and ignores the locale, returning FALSE for all non-ASCII characters. Also, unlike the standard library function, this takes a char, not an int, so don't call it on EOF, but no need to worry about casting to guchar before passing a possibly non-ASCII character in.

g_ascii_isprint ()

gboolean
g_ascii_isprint (gchar c);

Determines whether a character is a printing character.

Unlike the standard C library isprint() function, this only recognizes standard ASCII characters and ignores the locale, returning FALSE for all non-ASCII characters. Also, unlike the standard library function, this takes a char, not an int, so don't call it on EOF, but no need to cast to guchar before passing a possibly non-ASCII character in.

g_ascii_ispunct ()

gboolean
g_ascii_ispunct (gchar c);

Determines whether a character is a punctuation character.

Unlike the standard C library ispunct() function, this only recognizes standard ASCII letters and ignores the locale, returning FALSE for all non-ASCII characters. Also, unlike the standard library function, this takes a char, not an int, so don't call it on EOF, but no need to cast to guchar before passing a possibly non-ASCII character in.

g_ascii_isspace ()

gboolean
g_ascii_isspace (gchar c);

Determines whether a character is a white-space character.

Unlike the standard C library isspace() function, this only recognizes standard ASCII white-space and ignores the locale, returning FALSE for all non-ASCII characters. Also, unlike the standard library function, this takes a char, not an int, so don't call it on EOF, but no need to cast to guchar before passing a possibly non-ASCII character in.

g_ascii_isupper ()

gboolean
g_ascii_isupper (gchar c);

Determines whether a character is an ASCII upper case letter.

Unlike the standard C library isupper() function, this only recognizes standard ASCII letters and ignores the locale, returning FALSE for all non-ASCII characters. Also, unlike the standard library function, this takes a char, not an int, so don't call it on EOF, but no need to worry about casting to guchar before passing a possibly non-ASCII character in.

g_ascii_isxdigit ()

gboolean
g_ascii_isxdigit (gchar c);

Determines whether a character is a hexadecimal-digit character.

Unlike the standard C library isxdigit() function, this takes a char, not an int, so don't call it on EOF, but no need to cast to guchar before passing a possibly non-ASCII character in.

g_ascii_digit_value ()

gint
g_ascii_digit_value (gchar c);

Determines the numeric value of a character as a decimal digit. Differs from g_unichar_digit_value() because it takes a char, so there's no worry about sign extension if characters are signed.

g_ascii_xdigit_value ()

gint
g_ascii_xdigit_value (gchar c);

Determines the numeric value of a character as a hexadecimal digit. Differs from g_unichar_xdigit_value() because it takes a char, so there's no worry about sign extension if characters are signed.

g_ascii_strcasecmp ()

gint
g_ascii_strcasecmp (const gchar *s1,
                    const gchar *s2);

Compare two strings, ignoring the case of ASCII characters.

Unlike the BSD strcasecmp() function, this only recognizes standard ASCII letters and ignores the locale, treating all non-ASCII bytes as if they are not letters.

This function should be used only on strings that are known to be in encodings where the bytes corresponding to ASCII letters always represent themselves. This includes UTF-8 and the ISO-8859-* charsets, but not for instance double-byte encodings like the Windows Codepage 932, where the trailing bytes of double-byte characters include all ASCII letters. If you compare two CP932 strings using this function, you will get false matches.

Both s1 and s2 must be non-NULL.

g_ascii_strncasecmp ()

gint
g_ascii_strncasecmp (const gchar *s1,
                     const gchar *s2,
                     gsize n);

Compare s1 and s2 , ignoring the case of ASCII characters and any characters after the first n in each string. If either string is less than n bytes long, comparison will stop at the first nul byte encountered.

Unlike the BSD strcasecmp() function, this only recognizes standard ASCII letters and ignores the locale, treating all non-ASCII characters as if they are not letters.

The same warning as in g_ascii_strcasecmp() applies: Use this function only on strings known to be in encodings where bytes corresponding to ASCII letters always represent themselves.

g_ascii_strup ()

gchar *
g_ascii_strup (const gchar *str,
               gssize len);

Converts all lower case ASCII letters to upper case ASCII letters.

g_ascii_strdown ()

gchar *
g_ascii_strdown (const gchar *str,
                 gssize len);

Converts all upper case ASCII letters to lower case ASCII letters.

g_ascii_tolower ()

gchar
g_ascii_tolower (gchar c);

Convert a character to ASCII lower case.

Unlike the standard C library tolower() function, this only recognizes standard ASCII letters and ignores the locale, returning all non-ASCII characters unchanged, even if they are lower case letters in a particular character set. Also unlike the standard library function, this takes and returns a char, not an int, so don't call it on EOF but no need to worry about casting to guchar before passing a possibly non-ASCII character in.

g_ascii_toupper ()

gchar
g_ascii_toupper (gchar c);

Convert a character to ASCII upper case.

Unlike the standard C library toupper() function, this only recognizes standard ASCII letters and ignores the locale, returning all non-ASCII characters unchanged, even if they are upper case letters in a particular character set. Also unlike the standard library function, this takes and returns a char, not an int, so don't call it on EOF but no need to worry about casting to guchar before passing a possibly non-ASCII character in.

g_string_ascii_up ()

GString *
g_string_ascii_up (GString *string);

Converts all lowercase ASCII letters to uppercase ASCII letters.

g_string_ascii_down ()

GString *
g_string_ascii_down (GString *string);

Converts all uppercase ASCII letters to lowercase ASCII letters.

g_strup ()

gchar *
g_strup (gchar *string);

Converts a string to upper case.

g_strdown ()

gchar *
g_strdown (gchar *string);

Converts a string to lower case.

g_strcasecmp ()

gint
g_strcasecmp (const gchar *s1,
              const gchar *s2);

A case-insensitive string comparison, corresponding to the standard strcasecmp() function on platforms which support it.

g_strncasecmp ()

gint
g_strncasecmp (const gchar *s1,
               const gchar *s2,
               guint n);

A case-insensitive string comparison, corresponding to the standard strncasecmp() function on platforms which support it. It is similar to g_strcasecmp() except it only compares the first n characters of the strings.

g_strreverse ()

gchar *
g_strreverse (gchar *string);

Reverses all of the bytes in a string. For example, g_strreverse ("abcdef") will result in "fedcba".

Note that g_strreverse() doesn't work on UTF-8 strings containing multibyte characters. For that purpose, use g_utf8_strreverse().

g_ascii_strtoll ()

gint64
g_ascii_strtoll (const gchar *nptr,
                 gchar **endptr,
                 guint base);

Converts a string to a gint64 value. This function behaves like the standard strtoll() function does in the C locale. It does this without actually changing the current locale, since that would not be thread-safe.

This function is typically used when reading configuration files or other non-user input that should be locale independent. To handle input from the user you should normally use the locale-sensitive system strtoll() function.

If the correct value would cause overflow, G_MAXINT64 or G_MININT64 is returned, and ERANGE is stored in errno. If the base is outside the valid range, zero is returned, and EINVAL is stored in errno. If the string conversion fails, zero is returned, and endptr returns nptr (if endptr is non-NULL).

Since: 2.12

g_ascii_strtoull ()

guint64
g_ascii_strtoull (const gchar *nptr,
                  gchar **endptr,
                  guint base);

Converts a string to a guint64 value. This function behaves like the standard strtoull() function does in the C locale. It does this without actually changing the current locale, since that would not be thread-safe.

Note that input with a leading minus sign (-) is accepted, and will return the negation of the parsed number, unless that would overflow a guint64. Critically, this means you cannot assume that a short fixed length input will never result in a low return value, as the input could have a leading -.

This function is typically used when reading configuration files or other non-user input that should be locale independent. To handle input from the user you should normally use the locale-sensitive system strtoull() function.

If the correct value would cause overflow, G_MAXUINT64 is returned, and ERANGE is stored in errno. If the base is outside the valid range, zero is returned, and EINVAL is stored in errno. If the string conversion fails, zero is returned, and endptr returns nptr (if endptr is non-NULL).

Since: 2.2

g_ascii_strtod ()

gdouble
g_ascii_strtod (const gchar *nptr,
                gchar **endptr);

Converts a string to a gdouble value.

This function behaves like the standard strtod() function does in the C locale. It does this without actually changing the current locale, since that would not be thread-safe. A limitation of the implementation is that this function will still accept localized versions of infinities and NANs.

This function is typically used when reading configuration files or other non-user input that should be locale independent. To handle input from the user you should normally use the locale-sensitive system strtod() function.

To convert from a gdouble to a string in a locale-insensitive way, use g_ascii_dtostr().

If the correct value would cause overflow, plus or minus HUGE_VAL is returned (according to the sign of the value), and ERANGE is stored in errno. If the correct value would cause underflow, zero is returned and ERANGE is stored in errno.

This function resets errno before calling strtod() so that you can reliably detect overflow and underflow.

g_ascii_dtostr ()

gchar *
g_ascii_dtostr (gchar *buffer,
                gint buf_len,
                gdouble d);

Converts a gdouble to a string, using the '.' as decimal point.

This function generates enough precision that converting the string back using g_ascii_strtod() gives the same machine-number (on machines with IEEE compatible 64bit doubles). It is guaranteed that the size of the resulting string will never be larger than G_ASCII_DTOSTR_BUF_SIZE bytes, including the terminating nul character, which is always added.

g_ascii_formatd ()

gchar *
g_ascii_formatd (gchar *buffer,
                 gint buf_len,
                 const gchar *format,
                 gdouble d);

Converts a gdouble to a string, using the '.' as decimal point. To format the number you pass in a printf()-style format string. Allowed conversion specifiers are 'e', 'E', 'f', 'F', 'g' and 'G'.

The format must just be a single format specifier starting with %, expecting a gdouble argument.

The returned buffer is guaranteed to be nul-terminated.

If you just want to want to serialize the value into a string, use g_ascii_dtostr().

g_strtod ()

gdouble
g_strtod (const gchar *nptr,
          gchar **endptr);

Converts a string to a gdouble value. It calls the standard strtod() function to handle the conversion, but if the string is not completely converted it attempts the conversion again with g_ascii_strtod(), and returns the best match.

This function should seldom be used. The normal situation when reading numbers not for human consumption is to use g_ascii_strtod(). Only when you know that you must expect both locale formatted and C formatted numbers should you use this. Make sure that you don't pass strings such as comma separated lists of values, since the commas may be interpreted as a decimal point in some locales, causing unexpected results.

g_ascii_string_to_signed ()

gboolean
g_ascii_string_to_signed (const gchar *str,
                          guint base,
                          gint64 min,
                          gint64 max,
                          gint64 *out_num,
                          GError **error);

A convenience function for converting a string to a signed number.

This function assumes that str contains only a number of the given base that is within inclusive bounds limited by min and max . If this is true, then the converted number is stored in out_num . An empty string is not a valid input. A string with leading or trailing whitespace is also an invalid input.

base can be between 2 and 36 inclusive. Hexadecimal numbers must not be prefixed with "0x" or "0X". Such a problem does not exist for octal numbers, since they were usually prefixed with a zero which does not change the value of the parsed number.

Parsing failures result in an error with the G_NUMBER_PARSER_ERROR domain. If the input is invalid, the error code will be G_NUMBER_PARSER_ERROR_INVALID. If the parsed number is out of bounds - G_NUMBER_PARSER_ERROR_OUT_OF_BOUNDS.

See g_ascii_strtoll() if you have more complex needs such as parsing a string which starts with a number, but then has other characters.

Since: 2.54

g_ascii_string_to_unsigned ()

gboolean
g_ascii_string_to_unsigned (const gchar *str,
                            guint base,
                            guint64 min,
                            guint64 max,
                            guint64 *out_num,
                            GError **error);

A convenience function for converting a string to an unsigned number.

This function assumes that str contains only a number of the given base that is within inclusive bounds limited by min and max . If this is true, then the converted number is stored in out_num . An empty string is not a valid input. A string with leading or trailing whitespace is also an invalid input. A string with a leading sign (- or +) is not a valid input for the unsigned parser.

base can be between 2 and 36 inclusive. Hexadecimal numbers must not be prefixed with "0x" or "0X". Such a problem does not exist for octal numbers, since they were usually prefixed with a zero which does not change the value of the parsed number.

Parsing failures result in an error with the G_NUMBER_PARSER_ERROR domain. If the input is invalid, the error code will be G_NUMBER_PARSER_ERROR_INVALID. If the parsed number is out of bounds - G_NUMBER_PARSER_ERROR_OUT_OF_BOUNDS.

See g_ascii_strtoull() if you have more complex needs such as parsing a string which starts with a number, but then has other characters.

Since: 2.54

g_strchug ()

gchar *
g_strchug (gchar *string);

Removes leading whitespace from a string, by moving the rest of the characters forward.

This function doesn't allocate or reallocate any memory; it modifies string in place. Therefore, it cannot be used on statically allocated strings.

The pointer to string is returned to allow the nesting of functions.

Also see g_strchomp() and g_strstrip().

g_strchomp ()

gchar *
g_strchomp (gchar *string);

Removes trailing whitespace from a string.

This function doesn't allocate or reallocate any memory; it modifies string in place. Therefore, it cannot be used on statically allocated strings.

The pointer to string is returned to allow the nesting of functions.

Also see g_strchug() and g_strstrip().

g_strstrip()

#define             g_strstrip( string )

Removes leading and trailing whitespace from a string. See g_strchomp() and g_strchug().

g_strdelimit ()

gchar *
g_strdelimit (gchar *string,
              const gchar *delimiters,
              gchar new_delimiter);

Converts any delimiter characters in string to new_delimiter .

Any characters in string which are found in delimiters are changed to the new_delimiter character. Modifies string in place, and returns string itself, not a copy.

The return value is to allow nesting such as:

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g_ascii_strup (g_strdelimit (str, "abc", '?'))

In order to modify a copy, you may use g_strdup():

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reformatted = g_strdelimit (g_strdup (const_str), "abc", '?');
...
g_free (reformatted);

g_strescape ()

gchar *
g_strescape (const gchar *source,
             const gchar *exceptions);

Escapes the special characters '\b', '\f', '\n', '\r', '\t', '\v', '\' and '"' in the string source by inserting a '\' before them. Additionally all characters in the range 0x01-0x1F (everything below SPACE) and in the range 0x7F-0xFF (all non-ASCII chars) are replaced with a '\' followed by their octal representation. Characters supplied in exceptions are not escaped.

g_strcompress() does the reverse conversion.

g_strcompress ()

gchar *
g_strcompress (const gchar *source);

Replaces all escaped characters with their one byte equivalent.

This function does the reverse conversion of g_strescape().

g_strcanon ()

gchar *
g_strcanon (gchar *string,
            const gchar *valid_chars,
            gchar substitutor);

For each character in string , if the character is not in valid_chars , replaces the character with substitutor .

Modifies string in place, and return string itself, not a copy. The return value is to allow nesting such as:

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g_ascii_strup (g_strcanon (str, "abc", '?'))

In order to modify a copy, you may use g_strdup():

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reformatted = g_strcanon (g_strdup (const_str), "abc", '?');
...
g_free (reformatted);

g_strsplit ()

gchar **
g_strsplit (const gchar *string,
            const gchar *delimiter,
            gint max_tokens);

Splits a string into a maximum of max_tokens pieces, using the given delimiter . If max_tokens is reached, the remainder of string is appended to the last token.

As an example, the result of g_strsplit (":a:bc::d:", ":", -1) is a NULL-terminated vector containing the six strings "", "a", "bc", "", "d" and "".

As a special case, the result of splitting the empty string "" is an empty vector, not a vector containing a single string. The reason for this special case is that being able to represent an empty vector is typically more useful than consistent handling of empty elements. If you do need to represent empty elements, you'll need to check for the empty string before calling g_strsplit().

g_strsplit_set ()

gchar **
g_strsplit_set (const gchar *string,
                const gchar *delimiters,
                gint max_tokens);

Splits string into a number of tokens not containing any of the characters in delimiter . A token is the (possibly empty) longest string that does not contain any of the characters in delimiters . If max_tokens is reached, the remainder is appended to the last token.

For example the result of g_strsplit_set ("abc:def/ghi", ":/", -1) is a NULL-terminated vector containing the three strings "abc", "def", and "ghi".

The result of g_strsplit_set (":def/ghi:", ":/", -1) is a NULL-terminated vector containing the four strings "", "def", "ghi", and "".

As a special case, the result of splitting the empty string "" is an empty vector, not a vector containing a single string. The reason for this special case is that being able to represent an empty vector is typically more useful than consistent handling of empty elements. If you do need to represent empty elements, you'll need to check for the empty string before calling g_strsplit_set().

Note that this function works on bytes not characters, so it can't be used to delimit UTF-8 strings for anything but ASCII characters.

Since: 2.4

g_strfreev ()

void
g_strfreev (gchar **str_array);

Frees a NULL-terminated array of strings, as well as each string it contains.

If str_array is NULL, this function simply returns.

g_strconcat ()

gchar *
g_strconcat (const gchar *string1,
             ...);

Concatenates all of the given strings into one long string. The returned string should be freed with g_free() when no longer needed.

The variable argument list must end with NULL. If you forget the NULL, g_strconcat() will start appending random memory junk to your string.

Note that this function is usually not the right function to use to assemble a translated message from pieces, since proper translation often requires the pieces to be reordered.

g_strjoin ()

gchar *
g_strjoin (const gchar *separator,
           ...);

Joins a number of strings together to form one long string, with the optional separator inserted between each of them. The returned string should be freed with g_free().

g_strjoinv ()

gchar *
g_strjoinv (const gchar *separator,
            gchar **str_array);

Joins a number of strings together to form one long string, with the optional separator inserted between each of them. The returned string should be freed with g_free().

If str_array has no items, the return value will be an empty string. If str_array contains a single item, separator will not appear in the resulting string.

g_strv_length ()

guint
g_strv_length (gchar **str_array);

Returns the length of the given NULL-terminated string array str_array . str_array must not be NULL.

Since: 2.6

g_strv_contains ()

gboolean
g_strv_contains (const gchar * const *strv,
                 const gchar *str);

Checks if strv contains str . strv must not be NULL.

Since: 2.44

g_strv_equal ()

gboolean
g_strv_equal (const gchar * const *strv1,
              const gchar * const *strv2);

Checks if strv1 and strv2 contain exactly the same elements in exactly the same order. Elements are compared using g_str_equal(). To match independently of order, sort the arrays first (using g_qsort_with_data() or similar).

Two empty arrays are considered equal. Neither strv1 not strv2 may be NULL.

Since: 2.60

g_strv_builder_new ()

GStrvBuilder *
g_strv_builder_new (void);

Creates a new GStrvBuilder with a reference count of 1. Use g_strv_builder_unref() on the returned value when no longer needed.

Since: 2.68

g_strv_builder_ref ()

GStrvBuilder *
g_strv_builder_ref (GStrvBuilder *builder);

Atomically increments the reference count of builder by one. This function is thread-safe and may be called from any thread.

Since: 2.68

g_strv_builder_unref ()

void
g_strv_builder_unref (GStrvBuilder *builder);

Decreases the reference count on builder .

In the event that there are no more references, releases all memory associated with the GStrvBuilder.

Since: 2.68

g_strv_builder_add ()

void
g_strv_builder_add (GStrvBuilder *builder,
                    const char *value);

Add a string to the end of the array.

Since 2.68

g_strv_builder_addv ()

void
g_strv_builder_addv (GStrvBuilder *builder,
                     const char **value);

Appends all the strings in the given vector to the builder.

Since 2.70

g_strv_builder_add_many ()

void
g_strv_builder_add_many (GStrvBuilder *builder,
                         ...);

Appends all the given strings to the builder.

Since 2.70

g_strv_builder_end ()

GStrv
g_strv_builder_end (GStrvBuilder *builder);

Ends the builder process and returns the constructed NULL-terminated string array. The returned value should be freed with g_strfreev() when no longer needed.

g_strerror ()

const gchar *
g_strerror (gint errnum);

Returns a string corresponding to the given error code, e.g. "no such process". Unlike strerror(), this always returns a string in UTF-8 encoding, and the pointer is guaranteed to remain valid for the lifetime of the process.

Note that the string may be translated according to the current locale.

The value of errno will not be changed by this function. However, it may be changed by intermediate function calls, so you should save its value as soon as the call returns:

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int saved_errno;

ret = read (blah);
saved_errno = errno;

g_strerror (saved_errno);

g_strsignal ()

const gchar *
g_strsignal (gint signum);

Returns a string describing the given signal, e.g. "Segmentation fault". You should use this function in preference to strsignal(), because it returns a string in UTF-8 encoding, and since not all platforms support the strsignal() function.

G_ASCII_DTOSTR_BUF_SIZE

#define G_ASCII_DTOSTR_BUF_SIZE (29 + 10)

A good size for a buffer to be passed into g_ascii_dtostr(). It is guaranteed to be enough for all output of that function on systems with 64bit IEEE-compatible doubles.

The typical usage would be something like:

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char buf[G_ASCII_DTOSTR_BUF_SIZE];

fprintf (out, "value=%s\n", g_ascii_dtostr (buf, sizeof (buf), value));

enum GNumberParserError

Error codes returned by functions converting a string to a number.

Since: 2.54

G_NUMBER_PARSER_ERROR

#define G_NUMBER_PARSER_ERROR (g_number_parser_error_quark ())

Domain for errors returned by functions converting a string to a number.

Since: 2.54

G_STR_DELIMITERS

#define	 G_STR_DELIMITERS "_-|> <."

The standard delimiters, used in g_strdelimit().

GStrv

typedef gchar** GStrv;

A typedef alias for gchar**. This is mostly useful when used together with g_auto().

GStrvBuilder

typedef struct _GStrvBuilder GStrvBuilder;

A helper object to build a NULL-terminated string array by appending. See g_strv_builder_new().

Since: 2.68